Job Utrecht University, Faculty of Geosciences - 4 PhD researchers Paleoclimatology (1,0 fte per position)

Currently, we seek to fill four PhD-research positions within the Paleoclimatology group, which make part of a NWO-funded Vici program - entitled ”Evolution of astronomically paced climate changes from Greenhouse to Icehouse world” - granted to Dr. Lucas Lourens.

The Vici program aims to detect the non-linear response mechanisms within the global climate system to astronomical forcing using an integrated data-modeling comparison approach applied to four key intervals, which experienced different background pCO2 concentrations. These intervals comprise: (1) the onset of major Northern Hemisphere glaciations (~3 Ma) when pCO2 values declined below pre-industrial (~280 p.p.m.v.) values, (2) the mid-Pleistocene transition when dominant obliquity-paced glacial cycles culminated into a ~100-kyr rhythm, (3) the evolution of the Antarctic ice sheets from the Oligocene to the mid-Miocene (~25-12 Ma) when background pCO2 values were still well above pre-industrial values, and (4) the warmest period of the Cenozoic (~55-50 Ma), when pCO2 reached values of more than four times the present-day (~385 p.p.m.v.) value. The Vici program involves scientists (including two postdoctoral fellows) at Utrecht University, the Royal Netherlands Meteorological Institute (KNMI), and various European and US research groups.

Project Vici-I: Mid-Pleistocene climate transition (~1.85 Ma to Recent)
Project Vici-II: Early – Late Pliocene climate transition (~3.8 to ~2.4 Ma)
Project Vici-III: Late Oligocene - Middle Miocene climate transition (25 – 12 Ma)
Project Vici-IV: Late Paleocene – Early Eocene climate transition (~55 – 50 Ma)

Further details about these projects you'll find under  'additional information'.

We are looking for highly motivated individuals with a MSc or equivalent degree in Geology, Biology, Biogeology, Physical Geography, Climate and Atmospheric Sciences or related fields, which are highly interested in paleoclimate (i.e. stable isotope, climate modeling) research. Candidates are expected to communicate easily in English, both verbally and in writing.

The successful candidate will be offered a full-time PhD position, at first for one year. Contingent on a (yearly) satisfactory performance this may be extended to a total period of four years, with the specific intent that it results in a doctorate within this period. The first evaluation will take place approximately after 6 months of employment; the second after nine months." After nine months the decision will be made if an extension of the contract to a total period of four years will be offered to the employee.

Conditions are based on the Collective Labour Agreement of the Dutch Universities. The gross monthly salary starts at € 2,042.- in the first year and increases to € 2,612.- in the fourth year, and is supplemented by a holiday allowance of 8% per year and a year-end bonus of 8.3%. We also offer a pension scheme, a health insurance allowance and flexible employment conditions.

The Faculty of Geosciences offers education and research concerning the geosphere, biosphere, atmosphere and anthroposphere. With a population of 2,200 students (BSc and MSc) and 575 staff, the faculty is a strong and challenging organization. The Faculty is organized in four Departments: Innovation and Environmental Sciences, Earth Sciences, Physical Geography, and Human Geography and Urban and Regional Planning.

Department of Earth Sciences, Paleoclimatology

Research at the Department of Earth Sciences is organized through the Institute of Earth Sciences Utrecht (IVAU, or Instituut voor Aardwetenschappen Utrecht). The institute addresses the dynamics of System Earth at all temporal and spatial scales, thereby encompassing a broad field of the Earth sciences. IVAU's research is concentrated in two main research programmes, Geodynamics of the Solid Earth and Climate and Environment that embed five themes: (1) Earth structure, planetary dynamics, and geopotential fields, (2) Evolution and dynamics of the crust/lithosphere system, (3) Earth materials: properties and processes, (4) Paleoenvironments and paleoclimate, and (5) Environmental (geo)sciences and global change. These research themes are driven by 12 expert groups containing over 160 researchers (including PhD students and Postdoctoral fellows). Besides research, the institute runs various Master Degree Programmes in Earth sciences.

Project Vici-I: Mid-Pleistocene climate transition (~1.85 Ma to Recent)
The main goal of this PhD project is to untangle the linear, non-linear and stochastic mechanisms that have lead to the prolonged 80-100-kyr glaciations during the mid-Pleistocene transition and the timing of the major terminations using a data-modeling comparison approach. Emphasis will be on chronological issues associated with MIS12-15 and the impact of North Atlantic cold events on Mediterranean climates during this time interval. In first instance, high-resolution Mediterranean-based benthic and planktic stable oxygen isotope and geochemical records will be composed for the last 800,000 years to establish a full comparison with the global benthic isotope stack (LR04) and ice core (Epica) data. Secondly, these records will be extended down into the late Pliocene and treated by statistical methods and inverse modeling techniques (see also Vici-II project) to enable a comprehensive understanding of amongst others the end of mid-Pleistocene transition. This period characterizes a fundamental change in the climate state and is described by a series of notable events, such as a major reorganization in the carbon reservoir of the global ocean during Marine Isotope Stage 13 or the onset of the Mid-Brunhes dissolution interval (MBDI) between MIS 14 and 13.

Project Vici-II: Early – Late Pliocene climate transition (~3.8 to ~2.4 Ma)
The main goal of this PhD project is to constrain the phase, geometry and magnitude of the North American and Eurasian ice sheets during the early to late Pliocene climate transition. Emphasis will be on the linear, nonlinear and stochastic characteristics of the glacial-interglacial variations before and after ~2.75 Ma. For this purpose the stable oxygen isotope composition of benthic foraminifera and geochemical proxy records of Mediterranean Ocean Drilling Sites (see also Vici-I project) will be extended down into the Pliocene warm period (5.3 to ~3.0 Ma). The resulting stable isotope record will be used as input for an inverse modeling technique to reconstruct changes in ice volume and temperature and further analyzed by statistical methods. Quantification of the early Pliocene glacial response times is needed to improve our understanding of teleconnections between Northern Hemisphere temperatures (glaciations) and low-latitude climate dynamics. In addition, the expected results may shed new light upon the major and long-term Pliocene intensification of the Mediterranean outflow between 3.5-3.3 Ma and the outstanding cooling event during the Mammoth geomagnetic subchron. Finally, the outcome of the project will provide further constraints on the tidal dissipation effects that largely control the accuracy of the astronomical solution.

Project Vici-III: Late Oligocene - Middle Miocene climate transition (25 – 12 Ma)
The main aim of this PhD project is to reconstruct Antarctic ice sheet evolution through the late Oligocene to Middle Miocene (~25-12 Ma). Focus will be on the long-term astronomical perturbations in relation to changes in the carbon cycle and forcing mechanisms behind the periodic occurrence of ~100-kyr climate cycles during the Miocene. For this purpose high-resolution benthic foraminiferal oxygen isotope records will be obtained from ODP Site 1264 in the southwestern Atlantic (Walvis Ridge) and the recently drilled IODP Site 1334 in the equatorial Pacific. The resulting high–resolution astronomically-tuned stable isotope records in combination with inverse modeling will allow to independently documenting the small-scale ice-sheet expansions (Mi events) and associated sea level changes during the Miocene. In addition, they will resolve the high-resolution structure of the Early Miocene Climate Optimum (EMCO), which coincides with an important change in ocean circulation associated with the opening of the Farm Strait. 

Project Vici-IV: Late Paleocene – Early Eocene climate transition (~55 – 50 Ma)
The main aim of this PhD project is to reconstruct changes in deep ocean temperature and position of the lysocline and calcite composite depth during the early Eocene warming trend (~55-50 Ma), and their response to recurrent perturbations in the global carbon cycle. Emphasis will be on the astronomical pacing theory of extreme hyperthermal events, such as the ETM1 (PETM), ETM2 (Elmo) and ETM3 (“X” event), whether they are related to either long-term astronomical modulations or a stochastic process of any kind, such as the build-up and release of a large methane reservoir, which is phase locked to the eccentricity forcing. For this purpose high-resolution stable isotope measurements and geochemical analyses will be performed on ODP Leg 208 materials and land-based marine successions. The succession of ETM1 to 3 and perhaps yet unknown other Eocene hyperthermals offers the unique opportunity to study the response of the oceanic system to enhanced CO2 input at different background climate states associated with the late Paleocene-early Eocene warming trend. As such, the proposed investigations may provide additional constraints for carbon cycle models to identify the main carbon source that have initiated these extreme global warming events.

For further details contact Dr. Lucas Lourens at llourens@geo.uu.nl.